Airbag equipment installed on a fixed portion of an automobile or an airplane body in front of a seated occupant plays an important role in the protection against injury arising due to collision with the fixed portion of the car body or airplane during an accident. Airbags may be produced in a number of manners and from a number of different materials. However, airbags are typically formed, at least in part, from some type of woven textile material. Such textile materials are disclosed in U.S. Pat. Nos. 5,277,230 to Sollars, Jr. issued Jan. 11, 1994; 5,259,645 to Hirabayashi, et al. issued Nov. 9, 1993; 5,110,666 to Menzel, et al. issued May 5, 1992; 5,073,418 to Thornton, et al. issued Dec. 17, 1991; 5,011,183 to Thornton, et al. issued Apr. 30, 1991; 4,921,735 to Bloch issued May 1, 1990; and 3,814,141 to Iribe, et al. issued Jun. 4, 1974. The teachings of all of which are incorporated herein by reference.
Historically, fabrics for use in vehicle airbags have typically been formed using conventional Rapier weaving machines wherein the pick yarn is drawn mechanically across the warp. Such weaving practices have been successful in producing the high weave density, i.e. pick count, which is desired for structural stability in the fabric used to withstand inflation and collision forces when the airbag is deployed during an accident. Unfortunately, typical Rapier weaving machines are significantly slower than alternative weaving technology such as water-jet weaving.
In water-jet weaving, the pick yarn is drawn through the shed of the warp yarns by means of a stream of water which represents a much faster method of insertion than the mechanical Rapier. Heretofore, airbag fabrics incorporating yarn of approximately 420 denier have been woven on water-jet weaving machines at a maximum weave density of approximately 46.times.46 (warp.times.fill). As will be appreciated by those with skill in the art, this construction is lighter than the typical 49.times.49 fabric woven on conventional Rapier weaving machines. In order to compensate for the lower weave density achievable on water-jet weaving machines, the weaving has been performed using yarns having high breaking tenacities so as to provide improved strength in the final fabric despite the lighter weave construction.
As will be appreciated by those of skill in the art, yarns of high tenacity may require slashing with a chemical compound referred to as a sizing compound to enhance the mechanical integrity of the higher tenacity yarns during weaving. When weaving fabric for airbags, the size which is used is typically a polyacrylic acid although other polymers such as polyvinyl alcohol, polystyrene, and polyacetates may likewise be utilized. While the sizing compound is typically effective in enhancing the mechanical integrity of the high tenacity yarn, such sizing also tends to enclose yarn oils which may not be compatible with polymeric compounds used for coating the fabric prior to its formation into an airbag structure. Accordingly, the practice prior to the present invention has been to eliminate the sizing compound as well as the enclosed yarn oils by the scouring and drying of the fabric prior to effecting any coating operation.
As will be recognized, the addition of scouring and drying operations may tend to increase the cost for the overall production of fabric. Thus, it is of useful benefit to provide a fabric which may be used in an airbag and which is woven on a water-jet loom at high weave constructions such as are available on conventional Rapier machines while avoiding the need to use high tenacity yarns with sizing compounds applied thereto. Such an improvement permits the complete elimination of scouring the fabric to remove enclosed yarn oils since the oils are removed within the water stream during the weaving process itself.